Artificial muscles comprising an electrode pair having fan portions and artificial muscle assemblies including same

ABSTRACT

An artificial muscle includes an electrode pair including a first electrode and a second electrode. One or both of the first electrode and the second electrode includes a central opening. The first electrode and the second electrode each include two or more fan portions and two or more bridge portions. Each fan portion includes a first end having an inner length, a second end having an outer length, a first side edge extending from the second end, and a second side edge extending from the second end. The outer length is greater than the inner length. Each bridge portion interconnecting adjacent fan portions at the first end.

TECHNICAL FIELD

The present specification generally relates to apparatus and methods forfocused inflation on at least one surface of a device, and, morespecifically, apparatus and methods for utilizing an electrode pair todirect a fluid to inflate the device.

BACKGROUND

Current robotic technologies rely on rigid components, such asservomotors to perform tasks, often in a structured environment. Thisrigidity presents limitations in many robotic applications, caused, atleast in part, by the weight-to-power ratio of servomotors and otherrigid robotics devices. The field of soft robotics improves on theselimitations by using artificial muscles and other soft actuators.Artificial muscles attempt to mimic the versatility, performance, andreliability of a biological muscle. Some artificial muscles rely onfluidic actuators, but fluidic actuators require a supply of pressurizedgas or liquid, and fluid transport must occur through systems ofchannels and tubes, limiting the speed and efficiency of the artificialmuscles. Other artificial muscles use thermally activated polymerfibers, but these are difficult to control and operate at lowefficiencies.

One particular artificial muscle design is described in the paper titled“Hydraulically amplified self-healing electrostatic actuators withmuscle-like performance” by E. Acome, S. K. Mitchell, T. G. Morrissey,M. B. Emmett, C. Benjamin, M. King, M. Radakovitz, and C. Keplinger(Science 5 Jan. 2018: Vol. 359, Issue 6371, pp. 61-65). Thesehydraulically amplified self-healing electrostatic (HASEL) actuators useelectrostatic and hydraulic forces to achieve a variety of actuationmodes. However, HASEL actuator artificial muscles have a limitedactuator power per unit volume.

Accordingly, a need exists for improved artificial muscles withincreased actuator power per unit volume.

SUMMARY

In one embodiment, an artificial muscle includes an electrode pairincluding a first electrode and a second electrode, one or both of thefirst electrode and the second electrode including a central opening,the first electrode and the second electrode each including two or morefan portions, each fan portion including a first end having an innerlength, a second end having an outer length, a first side edge extendingfrom the second end, and a second side edge extending from the secondend, wherein the outer length is greater than the inner length, and twoor more bridge portions, each bridge portion interconnecting adjacentfan portions at the first end of the adjacent fan portions.

In another embodiment, an artificial muscle includes a housing having anelectrode region and an expandable fluid region, an electrode pairincluding a first electrode and a second electrode positioned in theelectrode region of the housing, the first electrode and the secondelectrode each including a plurality of fan portions, each fan portionincluding a first end having an inner length, a second end having anouter length, a first side edge extending from the second end, and asecond side edge extending from the second end, the outer length beinggreater than the inner length, and a plurality of bridge portions, eachbridge portion interconnecting adjacent fan portions at the first end,and a dielectric fluid housed within the housing, wherein the electrodepair is actuatable between a non-actuated state and an actuated statesuch that actuation from the non-actuated state to the actuated statedirects the dielectric fluid into the expandable fluid region.

In yet another embodiment, a method for actuating an artificial muscleassembly includes providing a voltage using a power supply electricallycoupled to an electrode pair of the artificial muscle, the artificialmuscle including a housing having an electrode region and an expandablefluid region, the electrode pair including a first electrode and asecond electrode positioned in the electrode region of the housing, thefirst electrode and the second electrode each including a plurality offan portions, each fan portion including a first end having an innerlength, a second end having an outer length, a first side edge extendingfrom the second end, and a second side edge extending from the secondend, the outer length being greater than the inner length, and aplurality of opposing bridge portions, each bridge portioninterconnecting adjacent fan portions at the first end of the adjacentfan portions, and a dielectric fluid housed within the housing, andapplying the voltage to the electrode pair of the artificial muscle,thereby actuating the electrode pair from a non-actuated state to anactuated state such that the dielectric fluid is directed into theexpandable fluid region of the housing and expands the expandable fluidregion.

These and additional features provided by the embodiments describedherein will be more fully understood in view of the following detaileddescription, in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments set forth in the drawings are illustrative and exemplaryin nature and not intended to limit the subject matter defined by theclaims. The following detailed description of the illustrativeembodiments can be understood when read in conjunction with thefollowing drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 schematically depicts an exploded view of an example artificialmuscle, according to one or more embodiments shown and described herein;

FIG. 2 schematically depicts a top view of the artificial muscle of FIG.1, according to one or more embodiments shown and described herein;

FIG. 3 schematically depicts a top view of another example artificialmuscle, according to one or more embodiments shown and described herein;

FIG. 4 schematically depicts a cross-sectional view of the artificialmuscle of FIG. 1 taken along line 4-4 in FIG. 2 in a non-actuated state,according to one or more embodiments shown and described herein;

FIG. 5 schematically depicts a cross-sectional view of the artificialmuscle of FIG. 4 in an actuated state, according to one or moreembodiments shown and described herein;

FIG. 6 schematically depicts a cross-sectional view of another exampleartificial muscle in a non-actuated state, according to one or moreembodiments shown and described herein;

FIG. 7 schematically depicts a cross-sectional view of the artificialmuscle of FIG. 6 in an actuated state, according to one or moreembodiments shown and described herein;

FIG. 8 schematically depicts an artificial muscle assembly including aplurality of the artificial muscles of FIG. 1, according to one or moreembodiments shown and described herein; and

FIG. 9 schematically depicts an actuation system for operating theartificial muscle of FIG. 1, according to one or more embodiments shownand described herein.

DETAILED DESCRIPTION

Embodiments described herein are directed to artificial muscles andartificial muscle assemblies that include a plurality of artificialmuscles. The artificial muscles described herein are actuatable toselectively raise and lower a region of the artificial muscles toprovide a selective, on demand inflated expandable fluid region. Theartificial muscles include a housing and an electrode pair. A dielectricfluid is housed within the housing, and the housing includes anelectrode region and an expandable fluid region, where the electrodepair is positioned in the electrode region. The electrode pair includesa first electrode, which may be fixed to a first surface of the housingand a second electrode, which may be fixed to a second surface of thehousing. The electrode pair is actuatable between a non-actuated stateand an actuated state such that actuation from the non-actuated state tothe actuated state directs the dielectric fluid into the expandablefluid region. This expands the expandable fluid region, raising aportion of the artificial muscle on demand. Further, the first electrodeand the second electrode each includes two or more fan portions and twoor more bridge portions interconnecting adjacent fan portions, and oneor both of the first electrode and the second electrode includes acentral opening positioned between the fan portions and encircles theexpandable fluid region. The fan portion provide an increased surfacearea for zippering toward the expandable fluid region when theartificial muscle is actuated to increase the force per unit volumeachievable. Various embodiments of the artificial muscles and theoperation of the artificial muscles are described in more detail herein.Whenever possible, the same reference numerals will be used throughoutthe drawings to refer to the same or like parts.

Referring now to FIGS. 1 and 2, an artificial muscle 100 is shown. Theartificial muscle 100 includes a housing 102, an electrode pair 104,including a first electrode 106 and a second electrode 108, fixed toopposite surfaces of the housing 102, a first electrical insulator layer110 fixed to the first electrode 106, and a second electrical insulatorlayer 112 fixed to the second electrode 108. In some embodiments, thehousing 102 is a one-piece monolithic layer including a pair of oppositeinner surfaces, such as a first inner surface 114 and a second innersurface 116, and a pair of opposite outer surfaces, such as a firstouter surface 118 and a second outer surface 120. In some embodiments,the first inner surface 114 and the second inner surface 116 of thehousing 102 are heat-sealable. In other embodiments, the housing 102 maybe a pair of individually fabricated film layers, such as a first filmlayer 122 and a second film layer 124. Thus, the first film layer 122includes the first inner surface 114 and the first outer surface 118,and the second film layer 124 includes the second inner surface 116 andthe second outer surface 120.

Throughout the ensuing description, reference may be made to the housing102 including the first film layer 122 and the second film layer 124, asopposed to the one-piece housing. It should be understood that eitherarrangement is contemplated. In some embodiments, the first film layer122 and the second film layer 124 generally include the same structureand composition. For example, in some embodiments, the first film layer122 and the second film layer 124 each comprises biaxially orientedpolypropylene.

The first electrode 106 and the second electrode 108 are each positionedbetween the first film layer 122 and the second film layer 124. In someembodiments, the first electrode 106 and the second electrode 108 areeach aluminum-coated polyester such as, for example, Mylar®. Inaddition, one of the first electrode 106 and the second electrode 108 isa negatively charged electrode and the other of the first electrode 106and the second electrode 108 is a positively charged electrode. Forpurposes discussed herein, either electrode 106, 108 may be positivelycharged so long as the other electrode 106, 108 of the artificial muscle100 is negatively charged.

The first electrode 106 has a film-facing surface 126 and an oppositeinner surface 128. The first electrode 106 is positioned against thefirst film layer 122, specifically, the first inner surface 114 of thefirst film layer 122. In addition, the first electrode 106 includes afirst terminal 130 extending from the first electrode 106 past an edgeof the first film layer 122 such that the first terminal 130 can beconnected to a power supply to actuate the first electrode 106.Specifically, the terminal is coupled, either directly or in series, toa power supply and a controller of an actuation system 400, as shown inFIG. 9. Similarly, the second electrode 108 has a film-facing surface148 and an opposite inner surface 150. The second electrode 108 ispositioned against the second film layer 124, specifically, the secondinner surface 116 of the second film layer 124. The second electrode 108includes a second terminal 152 extending from the second electrode 108past an edge of the second film layer 124 such that the second terminal152 can be connected to a power supply and a controller of the actuationsystem 400 to actuate the second electrode 108.

With respect now to the first electrode 106, the first electrode 106includes two or more fan portions 132 extending radially from a centeraxis C of the artificial muscle 100. In some embodiments, the firstelectrode 106 includes only two fan portions 132 positioned on oppositesides or ends of the first electrode 106. In some embodiments, the firstelectrode 106 includes more than two fan portions 132, such as three,four, or five fan portions 132. In embodiments in which the firstelectrode 106 includes an even number of fan portions 132, the fanportions 132 may be arranged in two or more pairs of fan portions 132.As shown in FIG. 1, the first electrode 106 includes four fan portions132. In this embodiment, the four fan portions 132 are arranged in twopairs of fan portions 132, where the two individual fan portions 132 ofeach pair are diametrically opposed to one another.

Each fan portion 132 has a first side edge 132 a and an opposite secondside edge 132 b. As shown, the first terminal 130 extends from thesecond end 136 of one of the fan portions 132 and is integrally formedtherewith. A channel 133 is at least partially defined by opposing sideedges 132 a, 132 b of adjacent fan portions 132 and, thus, extendsradially toward the center axis C. The channel 133 terminates at an end140 a of a bridge portion 140 interconnecting adjacent fan portions 132.

As shown in FIG. 1, dividing lines D are included to depict the boundarybetween the fan portions 132 and the bridge portions 140. The dividinglines D extend from the side edges 132 a, 132 b of the fan portions 132to the first end 134 of the fan portions 132 collinear with the sideedges 132 a, 132 b. It should be understood that dividing lines D areshown in FIG. 1 for clarity and that the fan portions 132 are integralwith the bridge portions 140. The first end 134 of the fan portion 132,which extends between adjacent bridge portions 140, defines an innerlength of the fan portion 132. Due to the geometry of the fan portion132 tapering toward the center axis C between the first side edge 132 aand the second side edge 132 b, the second end 136 of the fan portion132 defines an outer length of the fan portion 132 that is greater thanthe inner length of the fan portion 132.

Moreover, each fan portion 132 has a pair of corners 132 c defined by anintersection of the second end 136 and each of the first side edge 132 aand the second side edge 132 b of the fan portion 132. In embodiments,the corners 132 c are formed at an angle equal to or less than 90degrees. In other embodiments, the corners 132 c are formed at an acuteangle.

As shown in FIG. 1, each fan portion 132 has a first side length definedby a distance between the first end 134 of the fan portion 132 and thesecond end 136 of the fan portion 132 along the first side edge 132 aand the dividing line D that is collinear with the first side edge 132a. Each fan portion 132 also has a second side length defined by adistance between the first end 134 of the fan portion 132 and the secondend 136 of the fan portion 132 along the second side edge 132 b and thedividing line D that is collinear with the second side edge 132 b. Inembodiments, the first side length is greater than the second sidelength of the fan portion 132 such that the first electrode 106 has anellipsoid geometry.

The second end 136, the first side edge 132 a and the second side edge132 b of each fan portion 132, and the bridge portions 140interconnecting the fan portions 132 define an outer perimeter 138 ofthe first electrode 106. In embodiments, a central opening 146 is formedwithin the first electrode 106 between the fan portions 132 and thebridge portions 140, and is coaxial with the center axis C. Each fanportion 132 has a fan length extending from a perimeter 142 of thecentral opening 146 to the second end 136 of the fan portion 132. Eachbridge portion 140 has a bridge length extending from a perimeter 142 ofthe central opening 146 to the end 140 a of the bridge portion 140,i.e., the channel 133. As shown, the bridge length of each of the bridgeportions 140 is substantially equal to one another. Each channel 133 hasa channel length defined by a distance between the end 140 a of thebridge portion 140 and the second end of the fan portion 132. Due to thebridge length of each of the bridge portions 140 being substantiallyequal to one another and the first side length of the fan portions 132being greater than the second side length of the fan portions 132, afirst pair of opposite channels 133 has a channel length greater than achannel length of a second pair of opposite channels 133. As shown, awidth of the channel 133 extending between opposing side edges 132 a,132 b of adjacent fan portions 132 remains substantially constant due toopposing side edges 132 a, 132 b being substantially parallel to oneanother.

In embodiments, the central opening 146 has a radius of 2 centimeters(cm) to 5 cm. In embodiments, the central opening 146 has a radius of 3cm to 4 cm. In embodiments, a total fan area of each of the fan portions132 is equal to or greater than twice an area of the central opening146. It should be appreciated that the ratio between the total fan areaof the fan portions 132 and the area of the central opening 146 isdirectly related to a total amount of deflection of the first film layer122 when the artificial muscle 100 is actuated, as discussed herein. Inembodiments, the bridge length is 20% to 50% of the fan length. Inembodiments, the bridge length is 30% to 40% of the fan length. Inembodiments in which the first electrode 106 does not include thecentral opening 146, the fan length and the bridge length may bemeasured from a perimeter of an imaginary circle coaxial with the centeraxis C.

Similar to the first electrode 106, the second electrode 108 includestwo or more fan portions 154 extending radially from the center axis Cof the artificial muscle 100. The second electrode 108 includessubstantially the same structure as the first electrode 106 and, thus,includes the same number of fan portions 154. Specifically, the secondelectrode 108 is illustrated as including four fan portions 154.However, it should be appreciated that the second electrode 108 mayinclude any suitable number of fan portions 154.

Each fan portion 154 of the second electrode 108 has a first side edge154 a and an opposite second side edge 154 b. As shown, the secondterminal 152 extends from the second end 158 of one of the fan portions154 and is integrally formed therewith. A channel 155 is at leastpartially defined by opposing side edges 154 a, 154 b of adjacent fanportions 154 and, thus, extends radially toward the center axis C. Thechannel 155 terminates at an end 162 a of a bridge portion 162interconnecting adjacent fan portions 154.

As shown in FIG. 1, additional dividing lines D are included to depictthe boundary between the fan portions 154 and the bridge portions 162.The dividing lines D extend from the side edges 154 a, 154 b of the fanportions 154 to the first end 156 of the fan portions 154 collinear withthe side edges 154 a, 154 b. It should be understood that dividing linesD are shown in FIG. 1 for clarity and that the fan portions 154 areintegral with the bridge portions 162. The first end 156 of the fanportion 154, which extends between adjacent bridge portions 162, definesan inner length of the fan portion 154. Due to the geometry of the fanportion 154 tapering toward the center axis C between the first sideedge 154 a and the second side edge 154 b, the second end 158 of the fanportion 154 defines an outer length of the fan portion 154 that isgreater than the inner length of the fan portion 154.

Moreover, each fan portion 154 has a pair of corners 154 c defined by anintersection of the second end 158 and each of the first side edge 154 aand the second side edge 154 b of the fan portion 154. In embodiments,the corners 154 c are formed at an angle equal to or less than 90degrees. In other embodiments, the corners 154 c are formed at an acuteangle. As described in more detail herein, during actuation of theartificial muscle 100, the corners 132 c of the first electrode 106 andthe corners 154 c of the second electrode 108 are configured to beattracted to one another at a lower voltage as compared to the rest ofthe first electrode 106 and the second electrode 108. Thus, actuation ofthe artificial muscle 100 initially at the corners 132 c, 154 c resultsthe outer perimeter 138 of the first electrode 106 and the outerperimeter 160 of the second electrode 108 being attracted to one anotherat a lower voltage and reducing the likelihood of air pockets or voidsforming between the first electrode 106 and the second electrode 108after actuation of the artificial muscle 100.

As shown in FIGS. 1 and 2, in embodiments, the first side edge 154 a ofeach fan portion 154 has a first side length defined by a distancebetween the first end 156 of the fan portion 154 and the second end 158of the fan portion 154 along the first side edge 154 a and the dividingline D that is collinear with the first side edge 154 a. Each fanportion 154 also has a second side length defined by a distance betweenthe first end 156 of the fan portion 154 and the second end 158 of thefan portion 154 along the second side edge 154 b and the dividing line Dthat is collinear with the second side edge 154 b. In embodiments, thefirst side length is greater than the second side length of the fanportion 154 such that the second electrode 108 has an ellipsoid geometrycorresponding to the geometry of the first electrode 106.

The second end 158, the first side edge 154 a and the second side edge154 b of each fan portion 154, and the bridge portions 162interconnecting the fan portions 154 define an outer perimeter 160 ofthe second electrode 108. In embodiments, a central opening 168 isformed within the second electrode 108 between the fan portions 154 andthe bridge portions 162, and is coaxial with the center axis C. Each fanportion 154 has a fan length extending from a perimeter 164 of thecentral opening 168 to the second end 158 of the fan portion 154. Eachbridge portion 162 has a bridge length extending from the centralopening 168 to the end 162 a of the bridge portion 162, i.e., thechannel 155. As shown, the bridge length of each of the bridge portions162 is substantially equal to one another. Each channel 155 has achannel length defined by a distance between the end 162 a of the bridgeportion 162 and the second end of the fan portion 154. Due to the bridgelength of each of the bridge portions 162 being substantially equal toone another and the first side length of the fan portions 154 beinggreater than the second side length of the fan portions 154, a firstpair of opposite channels 155 has a channel length greater than achannel length of a second pair of opposite channels 155. As shown, awidth of the channel 155 extending between opposing side edges 154 a,154 b of adjacent fan portions 154 remains substantially constant due toopposing side edges 154 a, 154 b being substantially parallel to oneanother.

In embodiments, the central opening 168 has a radius of 2 cm to 5 cm. Inembodiments, the central opening 168 has a radius of 3 cm to 4 cm. Inembodiments, a total fan area of each of the fan portions 154 is equalto or greater than twice an area of the central opening 168. It shouldbe appreciated that the ratio between the total fan area of the fanportions 154 and the area of the central opening 168 is directly relatedto a total amount of deflection of the second film layer 124 when theartificial muscle 100 is actuated. In embodiments, the bridge length is20% to 50% of the fan length. In embodiments, the bridge length is 30%to 40% of the fan length. In embodiments in which the second electrode108 does not include the central opening 168, the fan length and thebridge length may be measured from a perimeter of an imaginary circlecoaxial with the center axis C.

As described herein, the first electrode 106 and the second electrode108 each have a central opening 146, 168 coaxial with the center axis C.However, it should be understood that the first electrode 106 does notneed to include the central opening 146 when the central opening 168 isprovided within the second electrode 108, as shown in the embodimentillustrated in FIGS. 6 and 7. Alternatively, the second electrode 108does not need to include the central opening 168 when the centralopening 146 is provided within the first electrode 106.

Referring again to FIG. 1, the first electrical insulator layer 110 andthe second electrical insulator layer 112 have a substantially ellipsoidgeometry generally corresponding to the geometry of the first electrode106 and the second electrode 108, respectively. Thus, the firstelectrical insulator layer 110 and the second electrical insulator layer112 each have fan portions 170, 172 and bridge portions 174, 176corresponding to like portions on the first electrode 106 and the secondelectrode 108. Further, the first electrical insulator layer 110 and thesecond electrical insulator layer 112 each have an outer perimeter 178,180 corresponding to the outer perimeter 138 of the first electrode 106and the outer perimeter 160 of the second electrode 108, respectively,when positioned thereon.

It should be appreciated that, in some embodiments, the first electricalinsulator layer 110 and the second electrical insulator layer 112generally include the same structure and composition. As such, in someembodiments, the first electrical insulator layer 110 and the secondelectrical insulator layer 112 each include an adhesive surface 182, 184and an opposite non-sealable surface 186, 188, respectively. Thus, insome embodiments, the first electrical insulator layer 110 and thesecond electrical insulator layer 112 are each a polymer tape adhered tothe inner surface 128 of the first electrode 106 and the inner surface150 of the second electrode 108, respectively.

Referring now to FIGS. 2, 4, and 5, the artificial muscle 100 is shownin its assembled form with the first terminal 130 of the first electrode106 and the second terminal 152 of the second electrode 108 extendingpast an outer perimeter of the housing 102, i.e., the first film layer122 and the second film layer 124. As shown in FIG. 2, the secondelectrode 108 is stacked on top of the first electrode 106 and,therefore, the first electrode 106, the first film layer 122, and thesecond film layer 124 are not shown. In its assembled form, the firstelectrode 106, the second electrode 108, the first electrical insulatorlayer 110, and the second electrical insulator layer 112 are sandwichedbetween the first film layer 122 and the second film layer 124. Thefirst film layer 122 is partially sealed to the second film layer 124 atan area surrounding the outer perimeter 138 of the first electrode 106and the outer perimeter 160 of the second electrode 108. In someembodiments, the first film layer 122 is heat-sealed to the second filmlayer 124. Specifically, in some embodiments, the first film layer 122is sealed to the second film layer 124 to define a sealed portion 190surrounding the first electrode 106 and the second electrode 108. Thefirst film layer 122 and the second film layer 124 may be sealed in anysuitable manner, such as using an adhesive, heat sealing, vacuumsealing, or the like.

The first electrode 106, the second electrode 108, the first electricalinsulator layer 110, and the second electrical insulator layer 112provide a barrier that prevents the first film layer 122 from sealing tothe second film layer 124 forming an unsealed portion 192. The unsealedportion 192 of the housing 102 includes an electrode region 194, inwhich the electrode pair 104 is provided, and an expandable fluid region196, which is surrounded by the electrode region 194. The centralopenings 146, 168 of the first electrode 106 and the second electrode108 define the expandable fluid region 196 and are arranged to beaxially stacked on one another. Although not shown, the housing 102 maybe cut to conform to the geometry of the electrode pair 104 and reducethe size of the artificial muscle 100, namely, the size of the sealedportion 190.

A dielectric fluid 198 is provided within the unsealed portion 192 andflows freely between the first electrode 106 and the second electrode108. A “dielectric” fluid as used herein is a medium or material thattransmits electrical force without conduction and as such has lowelectrical conductivity. Some non-limiting example dielectric fluidsinclude perfluoroalkanes, transformer oils, and deionized water. Itshould be appreciated that the dielectric fluid 198 may be injected intothe unsealed portion 192 of the artificial muscle 100 using a needle orother suitable injection device.

Referring now to FIG. 3, an alternative embodiment of an artificialmuscle 100′ is illustrated. It should be appreciated that the artificialmuscle 100′ is similar to the artificial muscle 100 described herein. Assuch, like structure is indicated with like reference numerals. Thefirst electrode 106 and the second electrode 108 of the artificialmuscle 100′ have a circular geometry as opposed to the ellipsoidgeometry of the first electrode 106 and the second electrode 108 of theartificial muscle 100 described herein. As shown in FIG. 3, with respectto the second electrode 108, a first side edge length of the first sideedge 154 a is equal to a second side edge length of the second side edge154 b. Accordingly, the channels 155 formed between opposing side edges154 a, 154 b of the fan portions 154 each have an equal length. Althoughthe first electrode 106 is hidden from view in FIG. 3 by the secondelectrode 108, it should be appreciated that the first electrode 106also has a circular geometry corresponding to the geometry of the secondelectrode 108.

Referring now to FIGS. 4 and 5, the artificial muscle 100 is actuatablebetween a non-actuated state and an actuated state. In the non-actuatedstate, as shown in FIG. 4, the first electrode 106 and the secondelectrode 108 are partially spaced apart from one another proximate thecentral openings 146, 168 thereof and the first end 134, 156 of the fanportions 132, 154. The second end 136, 158 of the fan portions 132, 154remain in position relative to one another due to the housing 102 beingsealed at the outer perimeter 138 of the first electrode 106 and theouter perimeter 160 of the second electrode 108. In the actuated state,as shown in FIG. 5, the first electrode 106 and the second electrode 108are brought into contact with and oriented parallel to one another toforce the dielectric fluid 198 into the expandable fluid region 196.This causes the dielectric fluid 198 to flow through the centralopenings 146, 168 of the first electrode 106 and the second electrode108 and inflate the expandable fluid region 196.

Referring now to FIG. 4, the artificial muscle 100 is shown in thenon-actuated state. The electrode pair 104 is provided within theelectrode region 194 of the unsealed portion 192 of the housing 102. Thecentral opening 146 of the first electrode 106 and the central opening168 of the second electrode 108 are coaxially aligned within theexpandable fluid region 196. In the non-actuated state, the firstelectrode 106 and the second electrode 108 are partially spaced apartfrom and non-parallel to one another. Due to the first film layer 122being sealed to the second film layer 124 around the electrode pair 104,the second end 136, 158 of the fan portions 132, 154 are brought intocontact with one another. Thus, dielectric fluid 198 is provided betweenthe first electrode 106 and the second electrode 108, thereby separatingthe first end 134, 156 of the fan portions 132, 154 proximate theexpandable fluid region 196. Stated another way, a distance between thefirst end 134 of the fan portion 132 of the first electrode 106 and thefirst end 156 of the fan portion 154 of the second electrode 108 isgreater than a distance between the second end 136 of the fan portion132 of the first electrode 106 and the second end 158 of the fan portion154 of the second electrode 108. This results in the electrode pair 104zippering toward the expandable fluid region 196 when actuated. Moreparticularly, zippering of the electrode pair 104 is initiated at thecorners 132 c of the first electrode 106 and the corners 154 c of thesecond electrode 108, as discussed herein. In some embodiments, thefirst electrode 106 and the second electrode 108 may be flexible. Thus,as shown in FIG. 4, the first electrode 106 and the second electrode 108are convex such that the second ends 136, 158 of the fan portions 132,154 thereof may remain close to one another, but spaced apart from oneanother proximate the central openings 146, 168. In the non-actuatedstate, the expandable fluid region 196 has a first height H1.

When actuated, as shown in FIG. 5, the first electrode 106 and thesecond electrode 108 zipper toward one another from the second ends 136,158 of the fan portions 132, 154 thereof, thereby pushing the dielectricfluid 198 into the expandable fluid region 196. As shown, when in theactuated state, the first electrode 106 and the second electrode 108 areparallel to one another. In the actuated state, the dielectric fluid 198flows into the expandable fluid region 196 to inflate the expandablefluid region 196. As such, the first film layer 122 and the second filmlayer 124 expand in opposite directions. In the actuated state, theexpandable fluid region 196 has a second height H2, which is greaterthan the first height H1 of the expandable fluid region 196 when in thenon-actuated state. Although not shown, it should be noted that theelectrode pair 104 may be partially actuated to a position between thenon-actuated state and the actuated state. This would allow for partialinflation of the expandable fluid region 196 and adjustments whennecessary.

In order to move the first electrode 106 and the second electrode 108toward one another, a voltage is applied by a power supply. In someembodiments, a voltage of up to 10 kV may be provided from the powersupply to induce an electric field through the dielectric fluid 198. Theresulting attraction between the first electrode 106 and the secondelectrode 108 pushes the dielectric fluid 198 into the expandable fluidregion 196. Pressure from the dielectric fluid 198 within the expandablefluid region 196 causes the first film layer 122 and the firstelectrical insulator layer 110 to deform in a first axial directionalong the center axis C of the first electrode 106 and causes the secondfilm layer 124 and the second electrical insulator layer 112 to deformin an opposite second axial direction along the center axis C of thesecond electrode 108. Once the voltage being supplied to the firstelectrode 106 and the second electrode 108 is discontinued, the firstelectrode 106 and the second electrode 108 return to their initial,non-parallel position in the non-actuated state.

It should be appreciated that the present embodiments disclosed herein,specifically, the fan portions 132, 154 with the interconnecting bridgeportions 140, 162, provide a number of improvements over actuators, suchas HASEL actuators, that do not include the fan portions 132, 154.Embodiments of the artificial muscle 100 including fan portions 132, 154on each of the first electrode 106 and the second electrode 108,respectively, increases the surface area and, thus, displacement at theexpandable fluid region 196 without increasing the amount of voltagerequired as compared to known HASEL actuators including donut-shapedelectrodes having a uniform, radially-extending width. In addition, thecorners 132 c, 154 c of the fan portions 132, 154 of the artificialmuscle 100 provide zipping fronts that result in focused and directedzipping along the outer perimeters 138, 160 of the first electrode 106and the second electrode 108 during actuation as compared to HASELactuators including donut-shaped electrodes.

Specifically, one pair of fan portions 132, 154 provides at least twicethe amount of actuator power per unit volume as compared to donut-shapedHASEL actuators, while two pairs of fan portions 132, 154 provide atleast four times the amount of actuator power per unit volume. Thebridge portions 140, 162 interconnecting the fan portions 132, 154 alsolimit buckling of the fan portions 132, 154 by maintaining the distancebetween the channels 133, 155 and the central openings 146, 168. Becausethe bridge portions 140, 162 are integrally formed with the fan portions132, 154, the bridge portions 140, 162 also prevent tearing and leakagebetween the fan portions 132, 154 by eliminating attachment locationsthat provide an increased risk of rupturing.

In operation, when the artificial muscle 100 is actuated, expansion ofthe expandable fluid region 196 produces a force of 20Newton-millimeters (N·mm) per cubic centimeter (cm³) of actuator volumeor greater, such as 25 N·mm per cm³ or greater, 30 N·mm per cm³ orgreater, 35 N·mm per cm³ or greater, 40 N·mm per cm³ or greater, or thelike. In one example, when the artificial muscle 100 is actuated by avoltage of 9.5 kilovolts (kV), the artificial muscle 100 provides aresulting force of 20 N.

Moreover, the size of the first electrode 106 and the second electrode108 is proportional to the amount of displacement of the dielectricfluid 198. Therefore, when greater displacement within the expandablefluid region 196 is desired, the size of the electrode pair 104 isincreased relative to the size of the expandable fluid region 196. Itshould be appreciated that the size of the expandable fluid region 196is defined by the central openings 146, 168 in the first electrode 106and the second electrode 108. Thus, the degree of displacement withinthe expandable fluid region 196 may alternatively, or in addition, becontrolled by increasing or reducing the size of the central openings146, 168.

As shown in FIGS. 6 and 7, another embodiment of an artificial muscle200 is illustrated. The artificial muscle 200 is substantially similarto the artificial muscle 100. As such, like structure is indicated withlike reference numerals. However, as shown, the first electrode 106 doesnot include a central opening, such as the central opening 146. Thus,only the second electrode 108 includes the central opening 168 formedtherein. As shown in FIG. 6, the artificial muscle 200 is in thenon-actuated state with the first electrode 106 being planar and thesecond electrode 108 being convex relative to the first electrode 106.In the non-actuated state, the expandable fluid region 196 has a firstheight H3. In the actuated state, as shown in FIG. 7, the expandablefluid region 196 has a second height H4, which is greater than the firstheight H3. It should be appreciated that by providing the centralopening 168 only in the second electrode 108 as opposed to both thefirst electrode 106 and the second electrode 108, the total deformationmay be formed on one side of the artificial muscle 200. In addition,because the total deformation is formed on only one side of theartificial muscle 200, the second height H4 of the expandable fluidregion 196 of the artificial muscle 200 extends further from alongitudinal axis perpendicular to the center axis C of the artificialmuscle 200 than the second height H2 of the expandable fluid region 196of the artificial muscle 100 when all other dimensions, orientations,and volume of dielectric fluid are the same.

Referring now to FIG. 8, an artificial muscle assembly 300 is shownincluding a plurality of artificial muscles, such the artificial muscle100. However, it should be appreciated that a plurality of artificialmuscles 100′ or artificial muscles 200 may similarly be arranged in astacked formation. Each artificial muscle 100 may be identical instructure and arranged in a stack such that the expandable fluid region196 of each artificial muscle 100 overlies the expandable fluid region196 of an adjacent artificial muscle 100. The terminals 130, 152 of eachartificial muscle 100 are electrically connected to one another suchthat the artificial muscles 100 may be simultaneously actuated betweenthe non-actuated state and the actuated state. By arranging theartificial muscles 100 in a stacked configuration, the total deformationof the artificial muscle assembly 300 is the sum of the deformationwithin the expandable fluid region 196 of each artificial muscle 100. Assuch, the resulting degree of deformation from the artificial muscleassembly 300 is greater than that which would be provided by theartificial muscle 100 alone.

Referring now to FIG. 9, an actuation system 400 may be provided foroperating an artificial muscle or an artificial muscle assembly, such asthe artificial muscles 100, 100′, 200 or the artificial muscle assembly300 between the non-actuated state and the actuated state. Thus, theactuation system 400 may include a controller 402, an operating device404, a power supply 406, and a communication path 408. The variouscomponents of the actuation system 400 will now be described.

The controller 402 includes a processor 410 and a non-transitoryelectronic memory 412 to which various components are communicativelycoupled. In some embodiments, the processor 410 and the non-transitoryelectronic memory 412 and/or the other components are included within asingle device. In other embodiments, the processor 410 and thenon-transitory electronic memory 412 and/or the other components may bedistributed among multiple devices that are communicatively coupled. Thecontroller 402 includes non-transitory electronic memory 412 that storesa set of machine-readable instructions. The processor 410 executes themachine-readable instructions stored in the non-transitory electronicmemory 412. The non-transitory electronic memory 412 may comprise RAM,ROM, flash memories, hard drives, or any device capable of storingmachine-readable instructions such that the machine-readableinstructions can be accessed by the processor 410. Accordingly, theactuation system 400 described herein may be implemented in anyconventional computer programming language, as pre-programmed hardwareelements, or as a combination of hardware and software components. Thenon-transitory electronic memory 412 may be implemented as one memorymodule or a plurality of memory modules.

In some embodiments, the non-transitory electronic memory 412 includesinstructions for executing the functions of the actuation system 400.The instructions may include instructions for operating the artificialmuscles 100, 100′, 200 or the artificial muscle assembly 300 based on auser command.

The processor 410 may be any device capable of executingmachine-readable instructions. For example, the processor 410 may be anintegrated circuit, a microchip, a computer, or any other computingdevice. The non-transitory electronic memory 412 and the processor 410are coupled to the communication path 408 that provides signalinterconnectivity between various components and/or modules of theactuation system 400. Accordingly, the communication path 408 maycommunicatively couple any number of processors with one another, andallow the modules coupled to the communication path 408 to operate in adistributed computing environment. Specifically, each of the modules mayoperate as a node that may send and/or receive data. As used herein, theterm “communicatively coupled” means that coupled components are capableof exchanging data signals with one another such as, for example,electrical signals via conductive medium, electromagnetic signals viaair, optical signals via optical waveguides, and the like.

As schematically depicted in FIG. 9, the communication path 408communicatively couples the processor 410 and the non-transitoryelectronic memory 412 of the controller 402 with a plurality of othercomponents of the actuation system 400. For example, the actuationsystem 400 depicted in FIG. 9 includes the processor 410 and thenon-transitory electronic memory 412 communicatively coupled with theoperating device 404 and the power supply 406.

The operating device 404 allows for a user to control operation of theartificial muscles 100, 100′, 200 or the artificial muscle assembly 300.In some embodiments, the operating device 404 may be a switch, toggle,button, or any combination of controls to provide user operation. As anon-limiting example, a user may actuate the artificial muscles 100,100′, 200 or the artificial muscle assembly 300 into the actuated stateby activating controls of the operating device 404 to a first position.While in the first position, the artificial muscles 100, 100′, 200 orthe artificial muscle assembly 300 will remain in the actuated state.The user may switch the artificial muscles 100, 100′, 200 or theartificial muscle assembly 300 into the non-actuated state by operatingthe controls of the operating device 404 out of the first position andinto a second position.

The operating device 404 is coupled to the communication path 408 suchthat the communication path 408 communicatively couples the operatingdevice 404 to other modules of the actuation system 400. The operatingdevice 404 may provide a user interface for receiving user instructionsas to a specific operating configuration of the artificial muscles 100,100′, 200 or the artificial muscle assembly 300. In addition, userinstructions may include instructions to operate the artificial muscles100, 100′, 200 or the artificial muscle assembly 300 only at certainconditions.

The power supply 406 (e.g., battery) provides power to the artificialmuscles 100, 100′, 200 or the artificial muscle assembly 300. In someembodiments, the power supply 406 is a rechargeable direct current powersource. It is to be understood that the power supply 406 may be a singlepower supply or battery for providing power to the artificial muscle100, 100′, 200 or the artificial muscle assembly 300. A power adapter(not shown) may be provided and electrically coupled via a wiringharness or the like for providing power to the artificial muscles 100,100′, 200 or the artificial muscle assembly 300 via the power supply406.

In some embodiments, the actuation system 400 also includes a displaydevice 414. The display device 414 is coupled to the communication path408 such that the communication path 408 communicatively couples thedisplay device 414 to other modules of the actuation system 400. Thedisplay device 414 may output a notification in response to an actuationstate of the artificial muscles 100, 100′, 200 or the artificial muscleassembly 300 or indication of a change in the actuation state of theartificial muscles 100, 100′, 200 or the artificial muscle assembly 300.Moreover, the display device 414 may be a touchscreen that, in additionto providing optical information, detects the presence and location of atactile input upon a surface of or adjacent to the display device 414.Accordingly, the display device 414 may include the operating device 404and receive mechanical input directly upon the optical output providedby the display device 414.

In some embodiments, the actuation system 400 includes network interfacehardware 416 for communicatively coupling the actuation system 400 to aportable device 418 via a network 420. The portable device 418 mayinclude, without limitation, a smartphone, a tablet, a personal mediaplayer, or any other electric device that includes wirelesscommunication functionality. It is to be appreciated that, whenprovided, the portable device 418 may serve to provide user commands tothe controller 402, instead of the operating device 404. As such, a usermay be able to control or set a program for controlling the artificialmuscles 100, 100′, 200 or the artificial muscle assembly 300 withoututilizing the controls of the operating device 404. Thus, the artificialmuscles 100, 100′, 200 or the artificial muscle assembly 300 may becontrolled remotely via the portable device 418 wirelessly communicatingwith the controller 402 via the network 420.

From the above, it is to be appreciated that defined herein areartificial muscles for inflating or deforming a surface of an object byselectively actuating the artificial muscle to raise and lower a regionthereof. This provides a low profile inflation member that may operateon demand.

It is noted that the terms “substantially” and “about” may be utilizedherein to represent the inherent degree of uncertainty that may beattributed to any quantitative comparison, value, measurement, or otherrepresentation. These terms are also utilized herein to represent thedegree by which a quantitative representation may vary from a statedreference without resulting in a change in the basic function of thesubject matter at issue.

While particular embodiments have been illustrated and described herein,it should be understood that various other changes and modifications maybe made without departing from the scope of the claimed subject matter.Moreover, although various aspects of the claimed subject matter havebeen described herein, such aspects need not be utilized in combination.It is therefore intended that the appended claims cover all such changesand modifications that are within the scope of the claimed subjectmatter.

What is claimed is:
 1. An artificial muscle comprising: an electrodepair comprising a first electrode and a second electrode, one or both ofthe first electrode and the second electrode including a centralopening, the first electrode and the second electrode each comprising:two or more fan portions, each fan portion including a first end havingan inner length, a second end having an outer length, a first side edgeextending from the second end, and a second side edge extending from thesecond end, wherein the outer length is greater than the inner length;and two or more bridge portions, each bridge portion interconnectingadjacent fan portions at the first end of the adjacent fan portions. 2.The artificial muscle of claim 1, further comprising: four fan portions;and four bridge portions, each bridge portion interconnecting a pair ofadjacent fan portions at adjacent side edges of the adjacent fanportions.
 3. The artificial muscle of claim 1, wherein: a channelextends between each pair of adjacent fan portions; the channel is atleast partially defined by opposing side edges of the adjacent fanportions; and the opposing side edges are parallel.
 4. The artificialmuscle of claim 1, wherein: a first side length of each fan portion isgreater than a second side length of each fan portion; the first sidelength extends from the first end to the second end of each fan portioncollinear with the first side edge; and the second side length extendsfrom the first end to the second end of each fan portion collinear withthe second side edge.
 5. The artificial muscle of claim 1 wherein: afirst side length of each fan portion is equal to a second side lengthof each fan portion; the first side length extends from the first end tothe second end of each fan portion collinear with the first side edge;and the second side length extends from the first end to the second endof each fan portion collinear with the second side edge.
 6. Theartificial muscle of claim 1, wherein each fan portion defines a cornerforming an acute angle at an intersection of the second end and each ofthe first side edge and the second side edge.
 7. The artificial muscleof claim 1, wherein the central opening has a radius between 3 cm and 4cm.
 8. The artificial muscle of claim 1, wherein a total fan area of thefan portions of one of the first electrode or the second electrode isequal to or greater than twice an area of a corresponding centralopening.
 9. The artificial muscle of claim 4, wherein each bridgeportion has a bridge length extending radially from the central opening,the bridge length being between 20% and 50% of an adjacent one of thefirst side length and the second side length of a corresponding fanportion.
 10. The artificial muscle of claim 1, further comprising: ahousing comprising an electrode region and an expandable fluid regiondefined by the central opening of the electrode pair; the electrode pairpositioned in the electrode region of the housing, the first electrodefixed to a first surface of the housing and the second electrode fixedto a second surface of the housing; a dielectric fluid housed within thehousing; wherein the electrode pair is actuatable between a non-actuatedstate and an actuated state such that actuation from the non-actuatedstate to the actuated state directs the dielectric fluid into theexpandable fluid region.
 11. An artificial muscle comprising: a housinghaving an electrode region and an expandable fluid region; an electrodepair comprising a first electrode and a second electrode positioned inthe electrode region of the housing, the first electrode and the secondelectrode each comprising: a plurality of fan portions, each fan portionincluding a first end having an inner length, a second end having anouter length, a first side edge extending from the second end, and asecond side edge extending from the second end, the outer length beinggreater than the inner length; and a plurality of bridge portions, eachbridge portion interconnecting adjacent fan portions at the first end;and a dielectric fluid housed within the housing, wherein the electrodepair is actuatable between a non-actuated state and an actuated statesuch that actuation from the non-actuated state to the actuated statedirects the dielectric fluid into the expandable fluid region.
 12. Theartificial muscle of claim 11, wherein: a first side length extends fromthe first end to the second end of each fan portion collinear with thefirst side edge; a second side length extends from the first end to thesecond end of each fan portion collinear with the second side edge; andthe first side length is greater than the second side length.
 13. Theartificial muscle of claim 12, wherein each fan portion includes acorner forming an acute angle at an intersection of the second end andeach of the first side edge and the second side edge.
 14. The artificialmuscle of claim 11, wherein the housing comprises: a first film layer; asecond film layer partially sealed to the first film layer to define asealed portion; and an unsealed portion surrounded by the sealedportion, wherein the electrode region and the expandable fluid region ofthe housing are positioned in the unsealed portion.
 15. The artificialmuscle of claim 14, wherein the first film layer and the second filmlayer are each biaxially oriented polypropylene films.
 16. Theartificial muscle of claim 11, further comprising: a first electricalinsulator layer fixed to an inner surface of the first electrode; and asecond electrical insulator layer fixed to an inner surface of thesecond electrode, wherein the first electrical insulator layer and thesecond electrical insulator layer each includes an adhesive surface andan opposite non-sealable surface.
 17. A method for actuating anartificial muscle, the method comprising: providing a voltage using apower supply electrically coupled to an electrode pair of the artificialmuscle, the artificial muscle comprising: a housing having an electroderegion and an expandable fluid region; the electrode pair comprising afirst electrode and a second electrode positioned in the electroderegion of the housing, the first electrode and the second electrode eachcomprising: a plurality of fan portions, each fan portion including afirst end having an inner length, a second end having an outer length, afirst side edge extending from the second end, and a second side edgeextending from the second end, the outer length being greater than theinner length; and a plurality of opposing bridge portions, each bridgeportion interconnecting adjacent fan portions at the first end of theadjacent fan portions; and a dielectric fluid housed within the housing;and applying the voltage to the electrode pair of the artificial muscle,thereby actuating the electrode pair from a non-actuated state to anactuated state such that the dielectric fluid is directed into theexpandable fluid region of the housing and expands the expandable fluidregion.
 18. The method of claim 17, wherein: a first side length extendsfrom the first end to the second end of each fan portion collinear withthe first side edge; a second side length extends from the first end tothe second end of each fan portion collinear with the second side edge;and the first side length is greater than the second side length. 19.The method of claim 18, wherein: each fan portion includes a cornerforming an acute angle at an intersection of the second end and each ofthe first side edge and the second side edge; and wherein each bridgeportion has a bridge length extending radially from a center axis, thebridge length being between 20% and 50% of an adjacent one of the firstside length and the second side length of a corresponding fan portion.20. The method of claim 17, wherein expanding the expandable fluidregion produces a force greater than 30 N·mm per cm³ of actuator volume.